Well, a lot's been said on this subject which is, at the end of the day, a completely unsubstantiated rumour.

Perhaps Panasonic will one day produce a FF compact. There are clearly people out there who will buy the latest thing regardless of its actual usefulness. Fuji seem to be producing rangefinder style cameras like there's no tomorrow and some people rave about them as the next great thing as each one appears. A few months down the line and practical testing reveals all sorts of problems like white 'halo' artefacts, etc.

M4/3 has made significant inroads into serious camera sales. It's prompted both Canon & Nikon into producing rival models, although all these have been down-specced so as not to offer too much competition to the bread and butter DSLRs (FF or otherwise). And a far more reliable rumour claims one of Canon next offerings will be the EOS B, a 'miniaturised' DSLR. I wonder why?

IMHO, I think Panasonic & Olympus have created a winning format. When sensors get better (as in better DR) there will come a point when image quality exceeds what can actually be reproduced, certainly in print. And I have no doubt that one day we will see CDAF blow PDAF out of the water; it's certainly more accurate.

For my purposes, as a professional user, the reduction in weight is an absolute joy. I see differential focussing as the only advantage FF has and that's possibly why Canon are all so fired up about FF. But that advantage will disappear (or be greatly reduced) as faster M4/3 lenses appear (which I'm sure they will). And not much has been said about the other side of the coin: The advantage of greater depth of field which smaller sensors have, which must please landscape photographers, if nobody else.

I can see nothing but a rosy future for M4/3 and I can see plenty of reasons why the 'big guns' would want to destabilise matters with baseless rumours...